This invention relates to a method and apparatus for processing photographic material. In particular, the invention relates to a method of delivering processing solutions to a processor.
Conventional processing of photographic material requires the use of large tanks of processing solutions. Each tank contains a processing solution such as developer, bleach, fixing solution or washing solution. The material is transported through each tank in turn. There is a tendency for the solutions to carry over from one tank to another leading to pollution of the solutions. Conventional processing has several other drawbacks. The temperatures which can be utilised are limited and therefore the process is slow. The composition of the solutions must be stable over long time periods in the processing tanks. Replenishment of the solutions is difficult to control. The processing apparatus is also very large due to the number of processing tanks.
To overcome the problems of conventional deep tank processing surface application of the processing chemicals was developed. In previous surface application methods a volume of solution is applied to the surface of the material being processed. However, previous surface application methods have several drawbacks.
In single use photographic processing machines deterioration of the processing solutions that can occur in large standing tanks is avoided by using small volumes of the processing solution to carry out a particular stage of the process. Once the stage is complete the solution is discarded. This requires that the solutions to be delivered must themselves be stable and not deteriorate by oxidation or evaporation. This can be accomplished by separating solutions into stable parts, mixing them just before use and also by using collapsible containers which prevent any major air ingress.
A process sequence or cycle is carried out by applying a succession of processing solutions according to a predetermined timing regime. The processing solutions can be supplied by a variety of means such as pumps and syringes. These means can be actuated automatically with a software control programmed according to any sequence or timing necessary. However, although this method is feasible it is complicated. The containers in which the solutions are stored must be substantially free from air to avoid deterioration. Pumps can fail or develop air bubbles which lowers the accuracy of the delivered volume. One way valves can stick and cause delivery failure. One way valves can also leak and cause delivery at the wrong time or position.
The method of the invention aims to overcome these problems and simplify delivery of the processing solutions. The method overcomes the problems by using a sequence of breakable sachets containing processing solution. The sachets are mounted on a flexible web in the order of the processing sequence.
According to the present invention there is provided a method of delivering processing solution to a processing device comprising the steps of, sealing a pre-measured volume of a processing solution within each of a plurality of sealed members, the sealed members being fixedly arranged on at least one movable elongate member and spaced apart along the length thereof in the order required for processing, the elongate member being movable relative to the processing area, and rupturing the sealed members in turn such that the processing solutions are released to the processing area in the correct order for processing.
The method of the invention is particularly useful for a type of single use device in which a single processing chamber is used for the whole process. A device of this type has been described in GB 0023091.2. In this device a small volume of processing solution is repeatedly spread on the surface of the photographic material until the time for the stage is reached after which the solution is removed by suction and the next solution is added. This is repeated for the entire process. The device consists of a rotating cylinder containing an agitation roller by means of which photographic material can be processed with very small volumes of solution. The processing solution can be very conveniently added onto the agitation roller by the method of the present invention.
In the method of the invention the volumes of processing solution are pre-measured at the site of manufacture of the sachets. The volumes should therefore be accurate. The pumps and valves required by conventional means of solution delivery are expensive, complicated and subject to variability. As these pumps and valves are eliminated the method is cheaper, less complicated and more reliable than conventional methods of solution delivery. In addition, since the processing solutions are sealed in the sachets prior to delivery they are free from aerial oxidation and evaporation.
A complete set of sachets to process one film can be linked together in the correct order of the processing stages and passed to the delivery point to be opened. This would always ensure the correct sequence of processing stages. In a single use processor the invention provides that a processing sequence can be changed by missing a particular stage by allowing the sachet to pass unopened.
In a single use processor the process can be very easily changed. For example, the process could be changed from colour negative to colour reversal by changing the pack of sachets and the software control. The same processor can therefore be used.
The handling of the processing chemicals is very easy and convenient since the chemicals are contained within the sachets.
Process control strips are not needed because the solutions are always fresh.